The invention relates to storage of strip material and to an apparatus for the processing of strip material, together with a photographic processing line.
Storage devices for strip material are being used at the present time in numerous different configurations and fields of application. An example of such a field of application is in photographic processing lines comprising a plurality of different processing stations. In such a processing line, initially the negative films are developed in a film developing station. In a subsequent copy machine, the so-called "printer", the negative films are copied onto a strip of a photosensitive photographic paper. The copy station is followed by a paper developing station, the so-called "wet part" in which the exposed paper is subjected to a wet chemical treatment and thus developed. Finally, in a subsequent terminal processing station the developed paper strip is cut into individual paper images and sorted. The negative films are cut into strips and subsequently the components belonging to a customer order (i.e., negative films and processed paper images) are packed into an inner pocket. The inner pocket is placed into the appropriate customer order packet, which then is returned to the customer or the agency transmitting the order.
Such a photographic processing line is described for example in U.S. Pat. No. 4,782,354. Because the individual processing stations in photographic processing lines usually operate independently of each other and the processing velocity of the individual stations may vary as the result of various effects, buffer storage devices are often inserted between the individual processing stations. The buffer storage devices are capable of intermediately storing the strip material to be processed, thereby compensating for fluctuations in the processing velocity of each station. For example, the exposure of the photosensitive paper strips in the printer may at times take place at a higher rate than the processing of the exposed strips in the wet part. If there is no intermediate storage device between the two stations, the printer would have to remain idle until the wet part is again able to process the paper. On the other hand, if the exposure of the paper strips in the printer occurs slower than the processing of the paper in the wet part, the latter would have to be idled until exposed paper is again supplied by the printer. This, however, must be avoided in the processing line, as the period of time during which the paper is exposed to the chemicals in the wet part must always be the same for a given paper, or otherwise the images could be destroyed.
A possible configuration of a photographic processing line having an intermediate storage to avoid such problems, is described in the aforementioned U.S. Pat. No. 4,782,354. A storage device described therein includes a frame, to which in a first plane a first support platform is stationarily fastened. A second support platform is provided in a second plane on said frame. The plane of the second support platform is parallel to the plane of the first platform. However, in contrast to the first support platform, the second support platform can slide in a manner such that while it always remains parallel to first support platform, it may be displaced, or moved toward or away from the first platform.
A plurality of rollers are connected with each support platform, with the rotating axles of the rollers extending parallel to the plane of the support platform involved. The paper is guided in a serpentine-like fashion over the rollers. To ensure a secure, tensioned guidance of the strip material over the rollers, but primarily to be able to equalize the aforementioned fluctuations of the working velocity of successive stations, reset springs are provided. The reset springs move the mobile support platform, together with the rollers mounted on it, in case of a variation in the operating velocity of a station. The reset springs move the mobile support platform toward or away from the stationary platform, depending on the nature of the variation (acceleration or slowing), so that on the one hand the strip material is always guided through the storage device in a secure and tensioned manner, and so that on the other hand none of the stations needs to be stopped to equalize fluctuations of the working rate.
A storage device of this type has several disadvantages. Firstly, the "inner life", or inner configuration, of the device is relatively complex, translating into an extensive production effort and thus high costs for the device. Furthermore, the threading of the strip material is very difficult and requires a considerable effort, again in view of the complex "inner life" of the device. Even if it is desired to avoid rethreading the strip material after a stoppage of the line (for example overnight), the aforementioned great effort is still required. That is, to avoid rethreading of the strip material to be processed upon the resumption of the operation, a so-called "blind strip" must run through the line until it is threaded through all of the storage devices (the strip material is attached to the blind strip). However, after the discontinuation of the operation (for example in the evening if the line is to be idled overnight), the line must run until the blind strip is passed completely through the storage device, which involves the loss of time. Other highly significant disadvantages of such a storage device is the enormous space it requires, together with its relatively low holding capacity. In the case where the receiving capacity for the strip material is to be very large, the storage device is extremely bulky and requires much space. This also poses large space requirements relative to the room in which the processing line is to be housed, which is especially disadvantageous in the development of space saving processing plants. Another storage device with similar disadvantages is described in U.S. Pat. No. 4,930,672.